I know this post is three months old, but I just come across it, and felt that we have very similar tastes
HD600 ~ These I bought new when they just come out (s/n <200!!) more than 20 years ago. I started using them with the headphone out of my Audiolab 8000A II integrated (that I still have as well), and later enjoyed them even more when paired with another ancient piece of audio, the Meier Corda HA-1, using the cross-feed filter in its lowest setting most of the time. I still find them the most comfortable, very accurate and very enjoyable. One of the drivers of the HD600 become damaged some years ago, and I substituted both of them for the newer silver drivers, and I have gone a few sets of ear-pads and headbands as well: talk about value-for-money and environmental sustainability!!
Ultimate Ears Reference Monitors (original version) ~ After decades with my trusty HD600, I was curious to hear what the new flagship HD800 sounded like. Also, my career had me starting to travel internationally, and I was looking for a compact travel headphone. I was living in Santa Cruz (CA) at the time, and was lucky enough to contact with Christian Tanimoto III (CEETEE) to try out his HD800
vs. UE CIEM (different models), and decided the UERM could make for a fantastic travel headphone. I use them mostly with a Creative Super X-fi (filetr off, sounds awful to me) or a Light Harmonic Geek Out 1000 (replaced by LH after my original GO100 failed under warranty) which I feel is marginally better. They are a PITA to remove, and even more to put on correctly for optimal seal, and after a couple of hours I can feel my ear wax starting to build up. For flying they have been a disappointment for no fault of their own, as I realized my ears clog up and I can not enjoy their terrific prowess. Fortunately I can easily enjoy them to the full once I am at my hotel room
Drop Dan Audio Ether CX ~ This are the newest addition, and bought them to be able to hear music without disturbing my partner, but being able to quickly remove them and respond a request, phone call or whatever. I was also curious about a planar (orthodynamic) headphone. I use them with a D50s>TCA HAP-1 (fan-tas-tic), EQ'd following Oratory settings, and find them very revealing and enjoyable. They leak a little, and I find them tiring after 2-3 hours, but I am quite satisfied with them.
I would be curious to hear Focal headphones, but there is really no need to change anything...
Due to work-related issues triggered by a health problem I do not have access to my speaker system, which I surely miss, but nevertheless I feel that we live in a golden era of sound quality, and now have not only the best sound I ever had, but also the easiest access to my music